Method for producing fiber boards



Jan. 8, 1963 E. JOHANSON METHOD FOR PRODUCING FIBER BOARDS Filed Jan. 13, 1960 INVENTOR ERIK JOHANSON av MW IDIDIiPIDIB'. "I

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United States Patent 3,072,523 METHOD FOR PRODUCING FIBER BOARDS Erik Johanson, Sollentuna, Sweden, assignor to Aktiebolaget Svenska Flaktfahriken, Nacka, Sweden Filed Jan. 13, 1960, Ser. No. 2,145 Claims priority, application Sweden, Jan. 19, 1959 6 Claims. (Cl. 162117) The present invention relates to a method for producing fiber boards, in which the basic material in the form of a fiber pulp in a known way is felted and formed into a continuous web in a so called wet section and thereafter treated in a press section.

A web formed in the above mentioned way contains large quantities of water even after having passed the press section, since it is hardly possible by mechanical dehydration to lower the water content below 60-65%. The remaining water must therefore be removed by drying the web. Owing to the high water content and the poor heat conductibility of the material a very long drying time is required for this purpose. a dryer of reasonable length it has therefore hitherto been necessary to make the dryer with .a large number of superimposed conveyors, on which the web-after having been cut into boards of a suitable length-is transported through the dryer. In order to successively feed the boards to the different conveyors of the dryer, a swingable conveyor must be arranged in front of the dryer, a so called tipple or hoist and in certain cases extensive arrangements are also required for the discharge of the boards, which arrangements not only require considerable space in length but also become expensive due to the complicated automatic means which are necessary for their operation.

The invention, the object of which is to eliminate the need for the last mentioned arrangements and by the possibility of a successive dehydration also to shorten the drying time, is characterized in that the wet web when formed is given a thickness sulficient for producing a web with a thickness equal to a multiple of the thickness of the final boards and that the web after a preliminary dehydration by pressing is split horizontally into two or more layers of equal thickness, which are parted and transported separately above each other, possibly being exposed to an additional pressing whereafter each of these layers in its turn is split horizontally into two or more layers, which in the same Way can be pressed, which procedure is repeated until webs of intended thickness are obtained, and that finally the webs being forwarded above each other are transported in parallel relation through a dryer having a number of decks corresponding to the number of layers whereafter the webs are brought together and trimmed by cutting to the desired size preferably when resting directly on each other. The separate webs can after the last splitting be patterned on one or both sides by being brought between embossing rolls, before the webs are brought into the drier.

The method according to the invention can also be modified in that the webs after the last splitting and dehydration are cut into boards of intended length and are brought into a multideck press for a simultaneous drying and pressing of the same to thin, hard boards.

The invention will now be closer described with refer- In order to use ence to the accompanying drawing which schematically ice felted and formed from a fiber pulp, passes from the last rolls 2 in a pressing section for the dehydration of the web into engagement with an endless saw-band 3 and a so called doctoring blade 4 by which means the web is split horizontally into two equally thick layers 5 and 6 respectively. These are parted and transported separately above each other, thereby being exposed to an additional dehydration by means of a pair of rolls 7 and 8 respectively. The layers are thereafter split in the same way by means of two similar saw-bands 9, 11 and two similar doctoring blades 10 and 12 respectively to produce four layers 13, 14, 15 and 16 which in their 'turn are dehydrated by means of pairs of rolls 17, 18, 19 and 20. The layers being finally divided as shown are thereafter fed into a dryer 21 provided with corresponding number of decks 22, 23, 24 and 25. Each deck can be equipped with rolls or conveyors or the drier can also be of the lately used design where the layers are transported air borne by means of the treatment medium used for drying. After the drying the layers are brought together and are trimmed by cutting resting directly on each other to desired size at 26 by means of a saw of known construction not shown in the drawing. In the drawing embossing means 27 are provided for each layer for patterning one side of the layer. Patterning can of course be made on both sides and the layers can also on one or both sides be covered with paint or in another way be treated on their surface before they are brought into the dryer.

In the case where one intends to make thin, hard boards the trimming is made already after the last splitting and dehydration whereafter the boards are brought into the multideck press for a simultaneous drying and pressing. This is shown in FIG. 2 wherein the web 31 is split and pressed to provide four layers 33, 34, 35, and 36 in a manner similar to the formation of the webs 13, 14, 15, and 16. The four layers are cut into lengths by a suitable shear at 37, and the lengths are then advanced into a multi-deck press 38 which both presses and dries the cut lengths to the desired condition. Embossing means may be provided at 39 which are similar to those shown at 27 in FIG. 1.

The arrangements'for the splitting and transport of the webs as well as construction of the dryer can be varied without departing from the idea of the invention.

What I claim is:

l. The process of making fiber boards, using dewatermg rolls and a multi-deck dryer, which comprises the following steps:

a. forming a fiber pulp slurry into a continuous web which has a thickness suflicient to form a plurality of boards of the desired thickness,

b. partly dewatering the multi-thickness web by pressing rolls, 1

c. splitting the multi-thickness web into a plurality of divided thinner webs after said pressing roll action,

d. dewatering each divided web by pressing rolls at a plurality of separate levels after the splitting has been eifected,

e. continuing the splitting and press-rolling action until webs for boards of the desired final thickness are produced and until the water content has been reduced sufiiciently for the dryer action,

f. bringing the webs at the last rolling action to separate levels required for a dryer,

g. and finally conveying all of said webs'at separate levels through said dryer having a plurality of decks located at the levels of the webs established by the last pressing rolls.

2. The method as set forth in claim 1, which further comprises:

h. embossing the final webs before they are brought into the dryer.

3. The method as set forth in claim 1, which further comprises:

i. bringing the plurality of Webs from the dryer together in superimposed relationship, one upon the other, in a multi-layer Web,

and severing the multi-layer web at intervals to form boards of the desired length.

4. The method as set forth in claim 3, further characterized by the fact that:

It. said layers from the dryer are brought together at 10 I I r l. severing the webs from the final dewatermg rolls 1 into proper length for the dryer before they are treated in the dryer. 6. The method as set forth in claim 5 which further comprises:

111. embossing the final Webs before they are brought to the dryer.

References Cited in the file of this patent UNITED STATES PATIENTS 1,894,778 Mason Ian. 17, 1933 2,092,966 Gay et al. Sept. 14, 1937 2,140,189 Mason Dec. 13, 1938 2,678,099 Provence May 11, 1954 2,950,225 Losse Aug. 23, 1960 

1. THE PROCESS OF MAKING FIBER BOARDS, USING DEWATERING ROLLS AND A MULTI-DECK DRYER, WHICH COMPRISES THE FOLLOWING STEPS: A. FORMING A FUBER PULP SLURRY INTO A CONTINUOUS WEB WHICH HAS A THICKNESS SUFFICIENT TO FORM A PLURALITY OF BOARDS OF THE DESIRED THICKNESS, B. PARTLY DEWATERING THE MULTI-THICKNESS WEB BY PRESSING ROLLS, C. SPLITTING THE MULTI-THICKNESS WEB INTO A PLURALITY OF DIVIDED THINNER WEBS AFTER SAID PRESSING ROLL ACTION, D. DEWATERING EACH DIVIDED WEB BY PRESSING ROLLS AT A PLURALITY OF SEPARATE LEVELS AFTER THE SPLITTING HAS BEEN EFFECTED, E. CONTINUING THE SPLITTING AND PRESS-ROLLING ACTION UNTIL WEBS FOR BOARDS OF THE DESIRED FINAL THICKNESS ARE PRODUCED AND UNTIL THE WATER CONTENT HAS BEEN REDUCED SUFFICIENTLY FOR THE DRYER ACTION, F. BRINGING THE WEBS AT THE LEAST ROLLING ACTION TO SEPARATE LEVELS REQUIRED FOR A DRYER, G. AND FINALLY CONVEYING ALL OF SAID WEBS AT SEPARATE LEVELS THROUGH SAID LAYER HAVING A PLURALITY OF DECKS LOCATED AT THE LEVELS OF THE WEB ESTABLISHED BY THE LAST PRESSING ROLLS. 